Mucopolysaccharidosis VI: cardiac involvement and the impact of enzyme replacement therapy

To describe cardiac abnormalities in patients with mucopolysaccharidosis (MPS) VI and to evaluate the impact of enzyme replacement therapy (ERT) on cardiac structure and function.

Data from electrocardiographic and echocardiographic evaluations were retrospectively collected from patients with MPS VI who are followed up at the Children's Hospital of Mainz.

The study included 44 (16 male and 28 female) patients. At baseline, valvular regurgitation (mainly aortic and mitral) and left ventricular (LV) volume overload were present in over half of patients. Other common cardiac manifestations were sinus tachycardia, LV hypertrophy, concentric LV remodelling, and pulmonary hypertension. One patient had left atrial dilation and one had congestive heart failure. Interventricular septal wall thickness and LV posterior wall thickness were above normal in most patients. Twenty five patients had a pre-ERT and at least one follow-up visit after ERT start. Mean follow-up after ERT start was 5.6 (SD 2.3) years. Despite the late onset (mean age 14.6 years) of treatment, ERT appeared to improve or arrest the progression of LV remodelling and LV hypertrophy and suspend the progression of cardiac valve disease.

MPS VI is associated with an array of cardiac manifestations. ERT appears to have some impact on cardiac structure and function when started late in life, but may have better long-term results when started during early infancy.